A microchannel reaction system, mainly consisting of a micromixer and a tubular reactor, was used to investigate the kinetics of butylation of 1-methyl-imidazole [MIM] for the synthesis of the ionic liquid 1-butyl-3-methylimidazolium bromide ([BMIM]Br). The low variance (sigma(2)(theta) = 0.019) of the residence time distribution, measured by a step stimuli-response tracer method, implies that this reaction system could be regarded as a plug flow reactor. As a fast and reliable method, the titration of bromide was established to determine the yield of [BMIM]Br. The reaction kinetics was studied by varying the molar ratio of 1-bromobutane [BrBu] to [MIM] (1.04-1.49) and temperature (75-90 degrees C). A second-order kinetics with respect to [MIM] and [BrBu] and an activation energy of 78.4 kJ/mol were found. (C) 2010 Elsevier B.V. All rights reserved.